In the prior art relating to raking machines and systems, such raking devices may be required to travel over long distances along a vertical or slightly inclined path, in close contact with a grate comb or bar screen, from the bottom of a water intake inlet to an emptying position above the grate or screen where collected debris is discharged or removed from the raking device during repetitious cycles. Under such operating conditions the base of the rake device may be mounted at ground level, e.g. above water surface level, while the longitudinal length of the raking mechanism may extend, both below and above such ground level. The environmental and climatical conditions in the region where such raking devices operate have dictated specification requirements for reliable operation of such devices, and few, if any prior art devices appear to be capable of meeting such requirements owing to the un reliability of the drive mechanisms used heretofore in such prior art devices. For example, where the device is utilized in a sheltered inhouse application the requirements are less stringent than when such devices ar utilized in an out-of-doors hostile near freezing temperature.
One prior art machine of the type to which the present invention relates is disclosed in U.S. Pat. No. 3,591,006, entitled "RAKING CLEANING TOOL", issued July 6, 1971, to Ignaz Daferner et al, which disclose means of guide tracks and driving gears coupled thereto for up and down motion along such track having a reversed portion at the bottom ends thereof whereby a continuous path of movement results for the driving gears. Another prior art example, is disclosed in U.S. Pat. No. 3,909,411, entitled "GRATE RAKE FOR CLEANING A GRATE ARRANGED IN A WATER CONDUIT", issued Sept. 30, 1975, to Eduard Angele, et al, which discloses the movements of a rake comb by an articulated arrangement of two cylinder piston units which are so arranged as to cause the rake to move in an arcute path as the rake comb travels the full length of the grate bars to remove accumulated materials on the grate. A third prior art device is disclosed in U.S. Pat. No. 4,222,878, entitled "RAKING EQUIPMENT FOR TRASHRACKS", issued Sept. 16, 1980, to Hans Hansson, which discloses two tube members being telescopically displaceable in parallel relation to each other and connected to each other by a block means, with pulleys and wires arranged at an upper end of each tube member to provide means for up and down displacement of one of the tubes with respect to the other tube which is fixed to a support frame.
The foregoing prior art devices and many others, fail to provide raking systems which are reliable for operation in harsh near freezing climatical conditions or regions, and also are not capable of avoiding damage to the up and down motion of the raking arm which may be caused by the raking arm encounting a large obstruction from objects which may become lodged in the grating comb or bar screen as the rake traverses its up and down path along the grate or screen.
Therefore, it is an object of the present invention to provide a raking system that is mechanically, hydraulically and electrically rugged and reliable for automatic continuous or intermitten manual operation in harsh near freezing climatical conditions or regions.
Another object of the present invention is the provision of a raking system which automatically overrides and by-passes large objects which may become lodged in a grating comb or bar screen so as to prevent damage to the raking means.
Yet another object of the present invention is the provision of a raking system whose mode of operation is controlled automatically by programmable computer logic circuits or by manually initiated instructions.
Still another object of the invention is the provision of a raking system which has fewer and more reliable actuating means for driving a raking arm up and down along its raking lengths which may be extensive.
While another object of the invention is the provision of a raking system in which a single worm screw device actuates and controls the displacement of a rake arm or boom in its extension and retraction motion.
While still another object of the present invention is the provision of a raking system in which a single cylinder piston actuated cable device actuates and controls the displacement of a rake arm in its extension and retraction motion.
While yet another object of the invention is the provision of a raking system in which the raking stroke may be in excess of twenty feet.